K2 / Proflex Riders Group
General => Tech Forum => Topic started by: Ryan856 on May 30, 2011, 03:44:49 pm
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Hi there, I recently bought a proflex 856 from a friend and after looking around the internet I came across this little group :) so where better to ask my question than here?
well, my 856 came with magura hs-22 hydraulic rim brakes which are slightly dated, so I have decided that I would like to install hydraulic disc brakes, but after flicking through a few forums I have seen various designs, but none with any instructions :(
I dont really know where to start when making the adapter, do I buy the brakes I want first? or is there a "universal" size to make the adapter that will let me fit many different manufacturers brakes?
If anyone has made an adapter before could you tell me what and how you did it if you have the time, or possibly scan (or post) a template that would be brilliant!
Many Thanks, Ryan Happy Riding!!
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Welcome.
I remember that there is a Hayes PDF that has the numerical dimensions for a weld on tab.
Here is a photo of a recent modification to an 856 swingarm.
(http://i1015.photobucket.com/albums/af280/shovelon/100_3206.jpg)
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That looks...oddly familiar...
(http://i5.photobucket.com/albums/y186/deusexaethera/bikes/CIMG4012.jpg)
;D
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Nice Work!!!!
:D :D :D
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That's just the primer, of course. I wish I'd gotten a better match on the color coat, but it's close enough that it's only noticeable if you look at it with an eye for finding something wrong with it. Other than that, it works great.
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Great job terry did there! Look's like it came from the factory like that ;)
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Welcome.
I remember that there is a Hayes PDF that has the numerical dimensions for a weld on tab.
Here's an example with a whopping 203mm disc, that should stop even my fat ar$e! <GRIN> actually the BB7 160mm's I have on my XP-X do the job very adequately!
http://www.hayesdiscbrake.com/wp-content/uploads/2010/04/98-17887.pdf (http://www.hayesdiscbrake.com/wp-content/uploads/2010/04/98-17887.pdf)
Col.
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Welcome.
I remember that there is a Hayes PDF that has the numerical dimensions for a weld on tab.
Here's an example with a whopping 203mm disc, that should stop even my fat ar$e! <GRIN> actually the BB7 160mm's I have on my XP-X do the job very adequately!
[url]http://www.hayesdiscbrake.com/wp-content/uploads/2010/04/98-17887.pdf[/url] ([url]http://www.hayesdiscbrake.com/wp-content/uploads/2010/04/98-17887.pdf[/url])
Col.
Perfect. That gives all the dimensions for the mount.
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Sweet! Even I can carve that out on my non-cnc machine.........when the house is finished :-[
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Great job terry did there! Look's like it came from the factory like that ;)
It does indeed. I had to sand the edges a bit to round them off and get rid of cutter marks from whatever tool he used to shape the bracket, but it's made of aluminum so it wasn't a lot of effort. I've had people who've spent tens of thousands on fleets of bikes give me double- and triple-takes when I tell them the bike pre-dates disc brakes and I had the bracket custom-welded. It just looks that legit -- as well it should, considering it's kinda important for it to not break off.
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Sweet! Even I can carve that out on my non-cnc machine.........when the house is finished :-[
Or send it to shovelon to have it done while you work on the house. When you get it back, it'll be an evening of spray-painting and wet-sanding, and it'll be good to go.
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Oh yeah, the HoFlex will get discs someday and shovelon will likely get the welding job. Further, the carbon fiber fork will be disc too. Meanwhile, I can't work on anything in the shop so I have to just ride the bike and clean the tires on the Fairlane....a lot.
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How are you going to attach the disc adapter to the carbon fork? Won't the higher leverage applied by the disc brake pose a risk of cracking the fork leg where the adapter is attached? It's one thing to have rim brakes applying nearly the same torque to the fork legs as is being applied to the wheel, but since a disc brake is so much smaller than the wheel the torque applied to the mounting point is many times higher than what the rider feels as the bike slows down. I'm not sure I'd want to use discs on something with a default failure mode similar to shattering glass.
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I wouldn't dream of point loading the fork leg at the mount. I still have carbon fiber stashed away and would use epoxy resin. Having 30 years of experience in composites helps a bit too. My plan would be to fab the mount from cf/epoxy and bond it with methacrylate based adhesive. It's the pits that my old shop was sold off and parted out or I could mount a fork leg on the dyno and take actual measurements of the deflection and compare with rim brakes.
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a lotta years, a lotta miles, a lotta hills - and still going strong.
my creation below - (used to have a 'how to make' in the How Tos somewhere)
(http://idriders.com/proflex/coppermine/albums/userpics/10008/normal_Front_Disc_Mount_closeup_finished~0.jpg)
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Click here (http://idriders.com/proflex/smf/index.php?topic=3664.0) for how to make a rear disc brake adapter.
No welding involved and no fancy tools other than a droill press. I used a bearing which required the use of a lather in order to reduce friction but a simple hole and thin teflon washer could be used.
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I had forgotten about your adapter OP. Early stages of CRS no doubt
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there is a whole bunch of other designs out there - most are using the axle as mounting point.... mine uses the 5 mm tapped hole that is already in the dropout ... time will tell if that is strong enough.
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! have a '98 Proflex 5000 with the carbon swing arm. But the dropouts are aluminum/steel(?) Is there a an aftermarket bracket I can mount to fit disc brakes on to that?
I'm not mechanically inclined to create my own nor do I have the machinging tools to do so. Hence my search for an aftermarket one. Or is there someone on here that makes them for a reasonable price? Or is anyone parting one out that they'd like to sell? :)
I have a standard Rock Shox front fork on there so I was able to mount a front disc. But I'd like to add a rear disc as well.
Thanks!
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there is an adapter by [http://2bgoods.com/Brake-Therapy-Disc-Brake-Conversion-Kit-For-26-MTB-135mm-1001.htm ] that will work for it... only others, one similar to this in ebay, { http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=360367377758&ssPageName=STRK:MEWAX:IT } or one custom done if you know someone.... K2 used to have one, and so did rapid descent, but neither are made or available anymore...I could've used one for my 5000 or 4500 frames also....I'm going the Brake Therapy adapter route instead...sux at $150 a pop :P
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I had one of the K2 OEM adapters on my 4000. It fit very well, using the oval hole in the dropout along with the 2 machined threaded holes in the dropout. This adapter is very nicely machined and sturdy and bolts right on with no modifications. My 4000 had an aluminum swing arm, so if the carbon swing arm uses the same shape dropout with the oval hole in it, it should work on it. It does not used the axle to hold it on. I'm considering selling it since I have sold the 4000 and no longer need it.
(http://i135.photobucket.com/albums/q137/glader60/Bike/K2%204000/brakemountinside_1.jpg)
(http://i135.photobucket.com/albums/q137/glader60/Bike/K2%204000/4000reardisk.jpg)
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your write up is still there Nick.....the pictures have gone walkabout somewhere but the words are still good
http://idriders.com/proflex/tech/tech_op2.shtml